#include <iostream>
#include <vector>
#include <numeric>

using namespace std;

int main() {
    vector<uint64_t> v {1};
    for (int i = 2; i <= 100; ++i) {
        uint64_t carry = 0;
        for (int j = 0; j < v.size(); ++j) {
            uint64_t tmp = v[j] * i + carry;
            v[j] = tmp % 10;
            carry = tmp / 10;
        }
        while (carry) {
            v.push_back(carry % 10);
            carry /= 10;
        }
    }
    cout << accumulate(v.begin(), v.end(), 0) << endl;
    // 648
}